Field of the Invention
The present invention relates to an end-modified conjugated diene polymer and a method for preparing the same.
Discussion of Related Art
Recently, as the interest in eco-friendly and energy-saving high functional tires rises, the research on the development of high functional rubbers with dynamic properties such as rolling resistance and wet resistance, mechanical properties, and machinability has been conducted in various ways.
In general, styrene-butadiene rubbers (hereinafter, ‘SBR’) or butadiene rubbers (hereinafter, ‘BR’) are used as rubbers for tires, and they are mainly manufactured by a solution polymerization method.
The solution polymerization method, which polymerizes a monomer among solvents using an organometallic compound as an initiator, to manufacture rubbers, is capable of adjusting a structure of monomer or polymer, a coupling rate, etc. The polymer manufactured according to said method has excellent rolling resistance and wet resistance, and thus said method is widely used for manufacturing rubbers for tires.
Additionally, according to the solution polymerization method, the cold flow at room temperature can be controlled by introducing a functional group into a part of polymer using a modifying agent, and machinability and dispersibility can be improved when combined with a reinforcing agent. Especially, dynamic properties of tires, such as wear resistance, rolling resistance, wet resistance, etc., may be improved by increasing compatibility with carbon black or silica, which is a reinforcing agent used, when combined in a rubber composition for tires.
According to U.S. Pat. No. 5,508,333, more excellent dynamic properties and mechanical properties may be acquired than the conventional rubber has by modifying molecular ends to alkoxysilane compounds including an epoxy group. However, it is difficult to control the coupling rate.
According to US Patent Publication No. 2010-0152369, the use of alkoxysilane compounds including primary amine substituted with hydrolysable protective groups as end modifying agents may reduce hysteresis of the tire manufactured therefrom. However, in this case, there is an economical limit resulting from the application of protective groups. Additionally, the cold flow is high, and accordingly, long-term storage stability may be reduced.
Thus, it is necessary to develop a conjugated diene polymer for tire rubber capable of increasing compatibility or miscibility with the reinforcing agents through end modification, and also improving mechanical and dynamic properties of the tire manufactured therefrom.